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Biomedical subjects

A D Russell

Publications and source records attributed to A D Russell.

At least 19 recordsLinked to original sources
PubMed1992

The nature and site of biocide-induced sublethal injury in Bacillus subtilis spores.

Spores of Bacillus subtilis NCTC 8236 exposed at 22 degrees C to test biocides (alkaline glutaraldehyde, an iodophor, Lugol's solution, sodium hypochlorite and sodium dichloroisocyanurate) demonstrated varying degrees of injury to stressing agents (sodium hydroxide, sodium lauryl sulphate, polymyxin B sulphate or cetylpyridinium chloride) incorporated into a recovery agar medium. This injury to stressing agents was expressed mainly during outgrowth.

Bacillus subtilis↗
PubMed1992

Effects of chlorhexidine diacetate on Candida albicans, C. glabrata and Saccharomyces cerevisiae.

The effects of chlorhexidine diacetate (CHA) on Candida albicans, C. glabrata and wild-type and mannan, and permeability mutants of Saccharomyces cerevisiae have been studied. A CHA concentration of 10 micrograms/ml had little lethal activity against the Candida strains, but was more effective against S. cerevisiae. Concentrations of 100 and especially 1000 micrograms/ml brought about a much more rapid death of cells. 2-Mercaptoethanol enhanced the activity of CHA to some extent. Some of the mutant strains of S. cerevisiae were rather more sensitive than the wild-type strain. The age of cultures of C. albicans and C. glabrata influenced their response to CHA.

Candida↗
PubMed1992

Mechanism of action of chlorhexidine diacetate and phenoxyethanol singly and in combination against gram-negative bacteria.

Chlorhexidine diacetate and the aromatic alcohol, phenoxyethanol in combination had an enhanced bacteriostatic action against Escherichia coli and Pseudomonas aeruginosa strains. Investigations of potassium (K+) ion leakage by means of a potassium electrode and a radioactive method, employing 86Rb, indicated that the combination accelerated the rate of leakage from the cell. Leakage of pentose was also found to be enhanced in the presence of the combination compared with either drug alone.

Anti-Infective Agents, Local↗
PubMed1992

Bacterial uptake of 14C-chlorhexidine diacetate and 14C-benzyl alcohol and the influence of phenoxyethanol and azolectin: studies with gram-negative bacteria.

The uptake of 14C-chlorhexidine (14C-CHA) by Pseudomonas aeruginosa and smooth, rough and deep rough strains of Escherichia coli was very rapid with maximum uptake occurring within 20 s. Despite the rapid binding, the lethal action of CHA, although concentration-dependent, is comparatively slow and occurs in minutes rather than seconds. This indicates that the initial rapid binding is followed by a second slower action, responsible for the lethal effects of CHA. The lethal action could be accelerated, particularly at modest concentrations of CHA, by the simultaneous presence of phenoxyethanol (POE) or benzyl alcohol (BZA), although the magnitude of the effect was small. Both alcohols had little effect on the binding of 14C-CHA, which does not explain the enhanced bactericidal action of CHA. Uptake of 14C-benzyl alcohol (14C-BZA) by the same strains showed very different patterns with slower and time-related binding. CHA had a marked effect on BZA absorption but no direct link was established between binding patterns and cell death. The CHA neutraliser, azolectin, removed bound CHA (in the presence or absence of POE) very efficiently even at contact times of only 20 s.

Anti-Infective Agents, Local↗
PubMed1991

Factors affecting conjugative transfer of plasmid pWG613, determining gentamicin resistance, in Staphylococcus aureus.

Factors that are known to influence plasmid transfer in bacterial populations were studied for the conjugative plasmid pWG613, which determined gentamicin resistance in Staphylococcus aureus. The transfer frequency was largely unaffected over a wide range of temperature (18-42 degrees C); pH also had little effect on the transfer frequency in the range 5.0-8.5. High cell density and log phase cultures were required for optimal plasmid transfer, as were donor:recipient ratios of 0.003-3.3.

Cetrimonium↗
PubMed1991

The effects of some halogen-containing compounds on Bacillus subtilis endospores.

Sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC) were more active against Bacillus subtilis 8236 spores in both viability and in germination and outgrowth studies than were polyvinylpyrrolidone-iodine (PVP-I) and Lugol's solution. Of the two chlorine compounds studied NaOCl proved to be the more active. The two iodine-containing compounds gave contrasting results with the Lugol's solution demonstrating increased antibacterial activity with increasing available iodine concentration. The antibacterial behaviour of PVP-I, however, reflected the more complex nature of aqueous iodine-surfactant mixtures. Initially, non-complexed iodine concentration (the active species) increased with increasing total available iodine concentration, resulting in increasing antibacterial activity. However, due to changes in the physical properties of the mixture, a maximum concentration of non-complexed iodine was reached so that a further increase in total available iodine resulted in a decrease in non-complexed iodine concentration and consequently a decrease in the antibacterial activity of the solution was observed. A greater inhibitory effect was observed in subsequent germination and outgrowth studies when spores were pre-treated with respective biocide than when untreated spores were added to germination media containing biocide at t = 0. This may reflect a combination of different contact times plus the neutralizing effect of the germination media on such halogen compounds.

Bacillus subtilis↗
PubMed1991

Comparative sensitivity to antibiotics and biocides of methicillin-resistant Staphylococcus aureus strains isolated from Saudi Arabia and Great Britain.

Methicillin-resistant Staphylococcus aureus (MRSA) isolated in Saudi Arabia and Great Britain were examined for susceptibility to antibiotics and biocides. The strains differed in their sensitivity patterns. None of the Saudi strains showed resistance to propamidine isethionate, but most of the British gentamicin methicillin-resistant Staph. aureus (GMRSA) strains were highly resistant to this compound and to some other nucleic acid-binding (NAB) compounds. Both groups showed a low level of resistance towards quaternary ammonium compounds (QACs), but resistance to these compounds was not associated with resistance to gentamicin in the Saudi strains. The aminoglycoside-resistant determinants were non-conjugative in these strains. Natural MRSA strains were good recipients for pWG613, but transferred this plasmid in reciprocal crosses at significantly lower rates.

Anti-Bacterial Agents↗
PubMed1991

Effect of some antibiotics and biocides on plasmid transfer in Staphylococcus aureus.

The effects of some antibiotics and biocides on the conjugative transfer of the Staphylococcus aureus gentamicin resistance plasmid pWG613 were investigated. Gentamicin and vancomycin were found to stimulate plasmid transfer frequency by 10- to 20-fold whereas methicillin and three inhibitors of protein synthesis each reduced it by various degrees. Most significantly, mupirocin inhibited plasmid transfer frequency by more than 1000-fold. All the biocides tested (cationic agents, sodium dodecyl sulphate and an organomercurial) reduced plasmid transfer.

Anti-Bacterial Agents↗
PubMed1990

Uptake of L-[14C]-alanine by glutaraldehyde-treated and untreated spores of Bacillus subtilis.

The effect of glutaraldehyde on the uptake of L-alanine, and subsequent germination, in spores of Bacillus subtilis NCTC 8236 was examined. Germination was induced by single amino acids, D-glucose and phosphate buffer at 37 degrees C. L-alanine was the best germinant of all amino acids tested. Pretreatment of spores with low concentrations of acid and alkaline glutaraldehyde inhibited subsequent germination, complete inhibition being observed at concentrations of 0.1% (w/v). This concentration also prevented the loss of heat resistance of spores placed in germination medium and exposed to 75 degrees C. Radioactive studies indicated that maximum uptake of L-alanine occurred after ca 30 min at 37 degrees C. Only 1.2% of available L-alanine was taken up during germination. Pretreatment of spores with glutaraldehyde did not interfere with L-alanine uptake at aldehyde concentrations up to 0.5% (w/v). However, this was significantly reduced at a glutaraldehyde concentration of 1.0% (w/v). Minimal differences were observed between acid and alkaline forms of the aldehyde. The results are discussed in terms of the mode of action of glutaraldehyde.

Alanine↗
PubMed1990

Sporicidal action of alkaline glutaraldehyde: factors influencing activity and a comparison with other aldehydes.

The sporicidal efficacy of glutaraldehyde (2% w/v) was investigated under various conditions. Numerous factors influenced its activity: method of spore production, inherent spore resistance characteristics, alkalination, storage time and storage temperature. The sporicidal action of 2% alkaline glutaraldehyde at room temperature was compared with that of other aldehydes and commercially available formulations. Cidex (glutaraldehyde) and Sporicidin (glutaraldehyde + phenol full strength) were the most effective, followed by 8% (w/v) formaldehyde and 10% (v/v) Gigasept, a formaldehyde-containing product. Five per cent (v/v) Gigasept and 10% (w/v) glyoxal also had good sporicidal activity, though that of Sporicidin (1:16) was poor. No activity was observed with 10% (w/v) butyraldehyde.

Aldehydes↗
PubMed1990

Bacterial spores and chemical sporicidal agents.

Bacterial spores are among the most resistant of all living cells to biocides, although the response depends on the stage of sporulation. The development of resistance to some agents such as chlorhexidine occurs much earlier in sporulation than does resistance to glutaraldehyde, which is a very late event. During germination or outgrowth or both, resistance is lost and the cells become as susceptible to biocides as nonsporulating bacteria. Mechanisms of spore resistance to, and the action of, biocides are discussed, and possible means of enhancing antispore activity are considered. The clinical and other uses of sporicidal and sporostatic chemical agents are described.

Disinfectants↗
PubMed1989

Alkali-induced revival of Bacillus spores after inactivation by glutaraldehyde.

Spores of Bacillus subtilis 168 were apparently fully inactivated by exposure to 2% (w/v) glutaraldehyde for 20 h but a few spores could be revived by further treatment with 10-100 mM NaOH. A similar effect was found with spores from a range of Bacillus species. A minimum concentration of 5% (w/v) glutaraldehyde was required to prevent the alkali-induced reactivation. The implications of these results for the use of glutaraldehyde as a sporicidal agent are discussed.

Aldehydes↗
PubMed1989

Uptake of 14C-chlorhexidine diacetate to Escherichia coli and Pseudomonas aeruginosa and its release by azolectin.

Uptake of 14C-labelled chlorhexidine diacetate (14C-CHA) by wild-type and envelope mutant strains of Escherichia coli and Pseudomonas aeruginosa was very rapid. Maximum uptake was observed within a contact time of 20 s with no additional binding on increased contact, and was concentration-dependent. In contrast to this rapid binding of 14C-CHA, bactericidal studies revealed that the lethal activity of low concentrations of unlabelled CHA was slow, although higher concentrations had a rapid effect. Comparison of a wild-type strain with its envelope mutants indicated that there was little difference in 14C-CHA uptake, in minimal inhibitory concentrations or in bactericidal activity. Azolectin was found to be an effective neutralising agent of biguanide action, but in in vitro agar tests and in reducing or removing the amount of 14C-CHA taken up by the cells.

Chlorhexidine↗